DE1929894B2 - DEVICE FOR PRODUCING KINEMATOGRAPHIC X-RAY PHOTOS WITH A PHOTOELECTRICALLY CONTROLLED VOLTAGE CONTROL CIRCUIT - Google Patents

Description

The achieved blackening of the X-ray films belong to an X-ray tube with a high-voltage neder both basic types. In this context rator to supply the X-ray tube, with a the blackening of the film is an expression for the device for generating luminescent screen images Degree of the darkening effect that is caused by the radiation emitted by the X-ray tube is that the film is exposed to radiation, S lung, with a cinematographic ca- and has an optimum of maximum contrast between the film recording of the Leuchtschinn images, see underexposure and overexposure on. One with a photodiode that emits the light of the Kind of such a system automatically presents the luminescent screen images exposed and one of the current intensity, expressed in mA, while the intensity of this light emits a corresponding current, which type automatically expresses the voltage in kV ίο as well as with one of the photodiode connected downstream As is known, cinematographic voltage control circuits require that of the x-ray tube X-ray recording equipment controls a largely supplied operating voltage so that the Heiautomatic Radiation intensity control, since the lightness of the Leuchtschinn images in a given density of the filmed body part is continuously held in the area.

dem can, so that such rapid changes in the 15 In view of the increasing use of ki-

Duration of exposure of each image of the film by nematographic X-ray recording devices

and / or in the radiation intensity required and in view of the increased requirements

the fact that even a skilled technician can determine the operational requirements for the degree of accuracy of the recording.

cannot set conditions quickly enough. body parts are nonsynchronous cinematographic

The automatic current control is seriously subject to X-ray recording devices because there are restrictions insofar as they practically correspond to the requirement that they allow an image sequence possible range of current changes, the ratio of more than 60 images per second, ratio 2: 1 up to 3: 1. The minimum furthermore variable pulse durations are desired, or maximum current levels are determined by the extremely short exposure noise level of the kinescope system due to certain techniques or by the required thermal load capacity of the X-ray tube at higher currents. Most of the known cinematographic X-ray images last at lower currents because of the thermal recording facilities that require automatic mixing with limitations of the X-ray tube.
Work current control, have a light meter. It is therefore the object of the invention to provide an automatic center zero point that must be controlled by a trained technically working cinematographic X-ray recorder who manually adjusts the voltage of the measuring device of the non-synchronous construction so that a zero setting is maintained. create that with high frame speeds and will hold. to work with variable pulse exposure times

On the other hand, conventional automatic operations allow the frame redaction voltage control systems to keep a light sensing device 35 in a predetermined range,
This task is performed in a device that reads or integrates the light and the type described in the primary winding last according to the invention is solved by the voltage applied to the output of the photodiode. Such automatic voltage control syncronizing exposure switch is connected, the star use either a rectifier phase controlled by thyratrons 40 after receiving a desired amount of light or semiconductor-controlled rectifier phase control for an image corresponding to the time integral of the tion or a motor-driven regulating transformer photodiode current emits a switching signal that tor . The automatic voltage control systems work via a switching circuit that disconnects the two to a greater extent automatically than the automatic current of the X-ray tube, that furthermore the current control systems see, however, they tend to re-45 voltage control circuit a minimum time gel oscillations. Limit switch, which operates after an adjustable mini

As conventional automatic voltage control time from the start of recording a single image systems emits the primary winding of the high-voltage trans- minimum time signal, a maximum transformer control, they are not with the non-synchronous limit switch, which is accordingly after a single Kinematographic systems and in particular 50 adjustable maximum times emit a maximum time signal, not to be brought into harmony with systems that have changeable and a logical circuit, their mutable Have pulse durations, since no attempt is made against the switching signal of the exposure switch, which Mi makes has been supplied to the intensity over the time duration nimalzeitsignal and the maximalzeitsignal to integrate when the time duration and the image is and which is formed and with its output speed as a means of controlling the tension 55 with a tension control device in the vary. X-ray tube supply circuit connected in this way

An X-ray device is already known, it is that when the switching signal of the exposure (USA. Patent 3 356 847), with which an automatic switch before the minimum time signal the Order is used, which inte- voltage control device in the sense of a grated and the exposure is influenced due to such an integration 60 voltage reduction that dagetegration completed. However, this known device has the effect when the switching signal of the exposure is received neither a control circuit for the energy switch after the maximum time signal a voltage supply the X-ray tube still increases the cinematography, while the look at camera. Tension control device not affected

It is also known (US Pat. No. 65) when the switching signal of the exposure switch

3 345 516, British patent specification 818 870 and USA.- after the minimum time signal, but before the

Patent 2 962 594) a device for the maximum time signal arrives,

provide cinematographic X-ray recordings with Preferably, the X-ray tube has a control grid

1 929 ^

^X 6

ter on, and the switching circuit is with this control various recording or viewing front grids connected and designed to be transmitted during alignments, e.g. B. a standing picture solution by the switching signal of the exposure alarm 20, a monitoring device 21 and a ters applies a reverse voltage to the control grid. The cinematographic camera 22. The still camera Tension control device can be a 5 20 can be a known standard design, the Have servomotor, which by the logical switching to record a certain sequence of radio waves is controlled and which in turn responds to a gram, which is subordinate to it at a later point in time for which chip searches fed to the X-ray tube can be used. Overwhelming works. transmission device 21 can be a vidicon for transmission

In a further embodiment of the invention, the image is shown on a television monitor in advance, so that an additional brightness control or the image can be provided directly on a luminescent screen, which can be displayed independently of the display, with none of the preparatory modes of the photoelectric exposure switch is shown in detail. The cinematographic camera 22, in conjunction, supplies an adjustment signal to the voltage control device. With the device designed according to the invention, a 16-mm or 35-mm camera can be achieved that flawless operation of the cinematographic in connection with a control circuit 23 is relevant to the present invention X-ray system a cinematographic recording of a is kontiin a manner that allows the overall to the tube nuierüchen sequence of images generated based on the put voltage between the desired limits 20 phosphor screen 18 α of images amplifier means is maintained 18th With the known minimal occurrences.

time and maximum time limit switches would be a sensing element 24, z. B. a normal photo of a change in the patient's position that of the diode, the energy supplied to the X-ray tube attached to the lens arrangement 19 is acceptable limit and represents the intensity of the image in which the values must be exceeded in order for an optimal lens arrangement 19 emitted light. That is achieved by processing the film in the camera. During the sensing element 24 produced signal of a known X-ray equipment in the case of screen brightness control circuit 25 is supplied via line a relatively high image sequence speeds not turn 25 α abandoned. The output of the brightness control free wall have worked, after the vorliegen- circuit 25 an automatic servo motor gestures invention, a virtually instantaneous activations 30 drivingly abandoned 26 via the line 25 b. The response to rapid changes in the density of the motor drive 26 to be powered is achieved in connection with an autotracing object, for example the body tension control device 27 of a patient. that works in such a way that it meets the constant

The invention in connection with voltage generator 12 via line 27 a and thus the drawing on the basis of an exemplary embodiment 35 shows the voltage that is finally applied to the X-ray tube 11 explained; The drawing of the embodiment is placed, controls the constant voltage generator FIG. 12 shows, in the form of a block diagram, an invention according to FIG. 12 and the voltage control device 27 so trained cinematographic X-ray as the servomotor drive 26 provide an adjustable recording facility again. In the drawing is the energy supply source for the X-ray tube 11. The means for producing lnematographiscber 40, brightness control circuit 25, may be hand-made x-rays with an X-ray tube 11 to adjust the voltage by a non-display with the associated switching arrangements in the control device set to a desired value Block diagram shown, which apply a constant tension.

voltage generator 12 and a switching circuit 13 The automatic setting of the voltage is

steer. The X-ray tube 11 is grid-controlled in a manner known per se 45 by using an exposure switch 28. The lines 12 a, 12 b and is sufficient, which is a light integrator, as is often used in FIG. 13 a, these switching arrangements and the tube direct film radiography technology is used, and with each other. A servo-controlled collimator 14 in which the light intensity over the exposure time is connected to a collimator servo system 15, which relates to each individual image. Its position in order to control the size of the X-ray beam bundle 16, 50 can be selected such that a Sidas emerges from it from the X-ray tube 11. Insofar as han- gnal is generated after an optimal FSmwärdelt it has been obtained in the case of the present invention in the tongue, as set out above. different instantaneous values of the light intensity

The drawing also indicates schematically a signal corresponding to a level from a photodiode 17 which is subjected to an X-ray diagnosis 29, the signals when the latter becomes visible. When the X-ray beam 16 penetrates the patient radiation of a direction 18 produced by the X-ray radiation within 17 and is exposed to a bath generated by an image intensifier unit 19, the BQd that is on becomes. The exposure switch 28 picks up this intensity signal from the photodiode 29 and integrates the fluorescent screen 18 α of the photodiode 29 and integrates the device 18 appears in its size with a signal over the time interval of the exposure. When the combined electron acceleration and deceleration value of the integral has reached a level that collapses in such a way that the image is amplified by an optimal, predetermined FUmschwenkenpe factor of about 5000 and corresponds to a gel, the exposure switch 28 a Si-Leuchtschinn 18 b is made visible. The BQd 65 signal via the line 28 £ to a logic circuit is then received by a lens arrangement 19 of known 30, which is referred to as a density computer, this type being recorded. Through this lens arrangement, the signal via the line 30 b further causes that the one Bfldaufteuspiegel 19 a has, the BQd in switching circuit 13, the X-ray tube 11 can be switched off

The logic circuit 30 receives two further signals via lines 31 α and 32 α , which are maximum and minimum time signals from a variable maximum time limit switch 31 and a variable minimum time limit switch 32. A line 31b connects the maximum time limit value switch 31 to the minimum time limit value switch 32 to maintain a relationship between the limit value switches, for example the minimum limit value for the exposure duration being a few specified percent smaller than the maximum limit value for the exposure duration. The maximum time limit switch 31 and the minimum time limit switch 32 can be set in such a way that they supply the logic circuit 30 with pulses which represent the selected maximum and minimum limit values for the exposure duration.

As stated above, the exposure switch 28 generates a signal in any case which, when the optimum value of the time integral of the exposure is reached, influences the logic circuit 30 so that it sends a signal to the circuit 13 via the line 30b, which switches off the X-ray tube 11. If the exposure switch 28 generates a signal via the lines 28 b and 30 b before the minimum time limit value switch 32 outputs a signal to the logic circuit 30, the latter also generates a second output signal when it receives the signal from the exposure switch. The first output signal is that which is fed into the switching circuit 13 in order to switch off the X-ray tube 11. The second output signal is used to drive the servo motor

26 via a line 30 α abandoned in order to set the voltage that is applied to the tube to a lower value. If, on the other hand, the exposure switch 28 does not generate a signal before the logic circuit 30 picks up a signal from the maximum time limit switch 31, the logic circuit 30 again generates two output signals, the first of which is that which the switching circuit 13 for switching off the X-ray tube 11 is abandoned, while the second output signal is applied to the servomotor drive 26 via the line 30 α in order to set the voltage to a higher value. This means that an output signal from the logic circuit 30 - when such a signal occurs via the line 30a - is used to automatically adjust the voltage which is ultimately transmitted to the X-ray tube 11 via the servomotor drive 26 and the automatic voltage control device

27 is fed, while the other output is the Switching circuit 13 controls No correction signal is sent from logic circuit 30 via line 30a given to the power supply system when the signal from the exposure switch 28 from the logical Circuit 30 during the time interval between the minimum and maximum clock signals is recorded.

In operating the facility, a typical situation would also require fluoroscopy, which usually every kmematographic image precedes During the fluoroscopy, the voltage is automatically controlled by the screen brightness 25 set. In particular, the tension is automatically increased with the hooves of the sensing element 24 regulated, with a normal reference amplifier, not shown cooperates within the screen brightness control circuit 25, which in turn the servomotor drive 26 and thus the automatic tension control device 27 controls. the Response time of the voltage control device 27 can be designed to divide a 60 kV range into three Seconds passed. This type of automatic tension control is available during fluoroscopy not new.

Assume that the radiographer has the

ίο has predetermined factors to be used during the cinematographic filming. For a typical example, he has set the cinematographic camera 22 so that it operates at a frame rate of 60 frames per second, he has set the variable maximum time limit switch 31 to five milliseconds and has selected a value of 200 mA for the tube current. The variable minimum time limit switch 32 has been designed and set in such a way that it gives a signal to the logic circuit 30 with a duration of 60% of that of the limit switch 31, which in the present case would correspond to three milliseconds.
When the technician is recording cinematographic film

«5 took power, he pressed one not shown Exposure switch that triggers the following processes:

1. The filament current of the X-ray tube is increased to 200 mA;

2. the image splitting mirror 19 α of the lens arrangement 19 is automatically adjusted so that the image provided by the fluorescent screen is directed into the camera 22;

3. Certain taps of the automatically controlled X-ray transformer are switched in this way that the tube load of 200 mA is compensated;

4. the motor of the cinematographic camera 22 is switched on;

5. all circuit components of the variable maximum time limit switch 31, the variable Minimum time limit switch 32, exposure switch 28 and voltage control device 26, 27 are excited:

6 it is placed a negative Abschaltvorspannung to the control grid of the X-ray tube 11 and 7, the current injection circuit to the primary winding of the high-voltage transformer, which is not shown in detail, is CLOSED ^SEH -

When the camera shutter opens, a light interruption switch 33, which is assigned to the shutter, triggers a positive pulse in the switching circuit 13 via a line 33 α. This positive

The pulse that is applied via the line 13 α cancels the negative grid bias and the X-ray tube 11 begins to conduct electricity. Now during the first image in a typical inspection process (arbitrarily assumed) the

X-ray intensity too high because the set Tension was too high. The exposure switch 28 causes the too high intensity to be integrated Via the exposure time a signal that switches off the tube so that the exposure time becomes shorter than the limit set by the minimum time limit switch 32 is set. Then the exposure time is shorter than three milliseconds. The logical one Circuit 30 recognizes this situation and

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testifies the second signal via the line 30 a, which controls the servomotor drive 26 in such a way that the voltage applied to the X-ray tube 11 is reduced. After three or four images the voltage will have dropped to a value at which the x-ray intensity is such that the exposure switch 28 will result in termination of the exposure in three milliseconds. The logic circuit 30 now recognizes that this is a perfect exposure, and the servomotor drive 26 is switched off because no signal from the logic circuit is given any more via the line 30 α . As long as the exposure switch 28 causes the tube 11 to be excited and so that each exposure time relates to an image for an interval between three and five milliseconds, the logic circuit 30 does not generate a correction signal, since the tube voltage is within the correct limit values in order to achieve an optimal blackening of the To produce films. On the other hand, if there is a change in the density of an examined body part which causes the exposure switch 28 to

glade take greater yields than five milliseconds, the logic circuit 30 recognizes this situation and generates the signal on the line 30 a, which turns the servo motor drive 26 and the supply voltage to the tube vergrößert..Solange the exposure switch 28, a timing between three milliseconds (minimum exposure period ) and five milliseconds (maximum exposure time), it is not necessary to adjust the servomotor drive 26.

The object of the invention was in connection with an embodiment of a cinematographic X-ray device explains that automatically within set exposure time limit values works that z. B. are caused by the sensitivity of a special film. The invention however, it is not restricted to the exemplary embodiment described and illustrated. For example Exposure time limits from 1 to: milliseconds and a 90 mm film can fin the.

1 sheet of drawings

Claims (3)

4. Device according to one of claims 1 to 3, characterized in that an additional patent claims: brightness control device (24, 25) is provided, which is independent of the mode of operation of the photo 1. Device for producing cinematographic 5 toelectric exposure switch (28) a reeving device X-ray recordings with an X-ray tube, control signal to the voltage control device a high-voltage generator for supply (26,27). tion of the X-ray tube, with a device for
Generation of fluorescent screen images by the
radiation emitted by the X-ray tube, with io a cinematographic recording camera for Film recording of the luminescent screen images, with
a photodiode, which the Lieht the
Fluorescent screen images is exposed and one of the Intensity of this light corresponding current 15 The invention relates to a device emits, as well as a voltage control circuit downstream of the photodiode for producing cinematographic X-ray recordings, which controls the operating voltage supplied to the men, and in particular to a device that automatically controls the energy that controls the X-ray tube so that the brightness of the luminescent screen is fed to a non-synchronous cinematographic X-ray image kept in a predetermined range.
is, characterized in that with pulse arrangements for the exact control of the output of the photodiode (29) an integrating intensity of the X-ray radiation per film image in the kinematic exposure switch (28), the tographic X-ray recording devices are known per se after recording a desired light . Two basic systems that have been used to a certain extent for an image corresponding temporal integrators are the primary pulse signal of the photodiode current, a switching signal system and the secondary pulse system. These systems emit that via a switching circuit (13) which control the energy in the primary or secondary shutdown of the current of the X-ray tube (11) windings of the X-ray high-voltage transformer, that furthermore the voltage control circuit gate. Since the primary voltage is an alternating voltage, a minimum time limit switch (32), which is 30, the primary pulse systems work synchronously, that is, after an adjustable minimum time from. B. with an image sequence of 60, took a single image at the beginning of a minimum time 30.15 or 7V- * images / sec synchronously with a 60 Hz signal emits, operated a maximum time limit value switch AC mains voltage. These systems ter (31), which emits a maximum time signal for cinematographic work in most maximum time, and 35 cases, which have a logic circuit (30) with controlled exposure, represent times per image of 16 msec and above work, the switching signal (28 b) of the exposure are, however, rapidly moving body parts recorded (28), the minimum time signal (32 a) and men, for example heart valves or cardiovascular, the maximum time signal (31 α) is supplied and systems in which The vessels and arteries that are so formed and move rapidly with their exit (30 α) 4o when the heart pumps blood into them has such a reason with a voltage control device (26, the use of primary pulse systems on 27) in the X-ray tube supply circuit Their relatively low image change is linked to the fact that when the switching signal arrives, frequencies, ie low number of exposures en (28 b) of the exposure switch (28) before the mini- per second, proved to be insufficient if the voltage control device 45 precisely controlled exposure times in the range of 3 in the sense of a voltage reduction in the time signal (32a) to work up to 5 msec per image,
is influenced that, on the other hand, when the so far are in secondary pulse systems either a Switching signal of the exposure switch (28) after a pair of grid-controlled switching tubes, so-called Sedem Maximum time signal (31 α) a voltage tetrode, or one by a bias voltage increase is effected while the voltage 50 grid controlled x-ray tube has been used to Control device (26, 27) is not influenced to control the energy supplied to the X-ray tube, if the switching signal of the exposure switch is secondary impulse systems, the tetrodes or latticed (28) after the minimum time signal (32 a) but before using controlled tubes are in cinematographidem Maximum time signal (31 α) arrives. see x-ray equipment used 2. Device according to claim 1, characterized in that 55 has a variable pulse duration from 2 to indicates that the X-ray tube (11) have a control about 12 msec. You do not work synchronously, grid and that the switching circuit are independent of the network frequency and use (13) connected to this control grid and so the cameras at variable speed, is designed that when triggered by the In addition, other secondary impulse systems are also Switching signal of the exposure switch (28) a 60 which also locks the grid-controlled X-ray tube to the control grid. have been used in systems that use a 3. Device according to claim 1 or 2, there work predetermined pulse duration, which is characterized in that the voltage is usually set to 4 msec. These systems control device have a servomotor (26) that works synchronously and has a mains frequency which is controlled by the logic circuit (30) from 60 Hz cameras at speeds of 60 and which in turn controls a setting 30, 15 and Vh frames per second. member (27) for the X-ray tube (11) trains- Conventional cinematographic X-rays performed Tension works. collection devices with automatic control of the